Field of the Invention
The present invention relates to a piston pump assembly of an electronic controlled brake device for a vehicle, and more particularly, to a piston pump assembly of an electronic controlled brake device for a vehicle, which actively reduces noise or vibration upon initial operation of the electronic controlled brake device or in a low frequency section, thereby improving ride comfort.
Description of the Related Art
Recently, electronic controlled brake systems have evolved into always-on systems, such as an active hydraulic booster or a smart cruise control (SCC) which allows a vehicle to maintain a constant speed, as well as an anti-lock brake system (ABS) or an electronic stability control system, which is activated in emergency situations.
One of problems occurring in an existing piston pump is that a flow of a working fluid is opened and closed at a high speed due to chattering phenomenon of an outlet ball provided in an outlet housing of the pump at a motor speed in a low frequency section, and thus, serious hydraulic pulsation occurs as illustrated in a graph of FIG. 9, causing noise.
A driver easily feels small vibration or noise when the electronic controlled brake system is driven. Therefore, there is a need for a technology and a device which can reduce noise and vibration.